Advanced Materials 29, 1606370 (2017)

Solar cell generates electrical energy from light one via pulling excited carrieraway under built-in asymmetry. Doped semiconductor with antireflection layeris general strategy to achieve this including crystalline silicon (c-Si) solar cell.However, loss of extra energy beyond band gap and light reflection in particularwavelength range is known to hinder the efficiency of c-Si cell. Here, itis found that part of short wavelength sunlight can be converted into polarizationelectrical field, which strengthens asymmetry in organic-c-Si heterojunctionsolar cell through molecule alignment process. The light harvestedby organometal trihalide perovskite nanoparticles (NPs) induces molecularalignment on a conducting polymer, which generates positive electricalsurface field. Furthermore, a “field-effect solar cell” is successfully developedand implemented by combining perovskite NPs with organic/c-Si heterojunctionassociating with light-induced molecule alignment, which achieves anefficiency of 14.3%. In comparison, the device with the analogous structurewithout perovskite NPs only exhibits an efficiency of 12.7%. This finding providesa novel concept to design solar cell by sacrificing part of sunlight to provide“extra” asymmetrical field continuously as to drive photogenerated carriertoward respective contacts under direct sunlight. Moreover, it also points outa method to combine promising perovskite material with c-Si solar cell.